OverviewThe Zerg Swarm
StarCraft II: Heart of the Swarm is the second chapter in the StarCraft II trilogy. Heart of the Swarm will focus on the bestial, vicious Zerg collective, known as the Swarm. Swarm will chronologically come after StarCraft II: Wings of Liberty, the Terran chapter, and before StarCraft II: Legacy of the Void, the Protoss chapter.
Heart of the Swarm was originally under little-to-no development beyond the concept stage, since Wings of Liberty was the main focus of the initial StarCraft II development team. The StarCraft II "trilogy" was announced at Blizzcon 2008 and was met with some positive feedback, though there was much more negative reaction on Internet forums from users who accused Blizzard of merely splitting up the three campaigns so they could charge more money for each than for a single amalgamated product. Blizzard claims that the decision to split the campaign into three separate products was to ensure a more complete and epic story, with each of the campaigns being equal in length to the total length of the three campaigns in the original StarCraft. Whether this is true or not remains to be seen. Now that Wings of Liberty has launched, it is expected that Blizzard has moved on to working directly on Heart of the Swarm.Sarah Kerrigan
What is known about Heart of the Swarm is that the campaign will centre around Sarah Kerrigan, the self-styled "Queen of Blades". Kerrigan is a former Terran agent, mutated and infested into a powerful Zerg/Human hybrid, who is fighting to maintain and expand her control over the recently divided Zerg Swarm after she was stripped of her powers when she was purified at the end of Wings of Liberty. Kerrigan is still a Zerg/Human hybrid, but has regained her original personality, and lost her ability to control all Zerg everywhere with a thought, and will have to regain her powers to live up to the Overmind's prophecy that only she, as leader of the Swarm, can stop the "Dark Voice" character from wiping out the Terrans, the Protoss, and the Zerg. The campaign will have you progressing through missions to return Kerrigan to a semblance of her original strength using mutations, as she fights to regain control of the Swarm.
Heart of the Swarm is scheduled to be released on March 12, 2013. Unfortunately, it has been stated that Wings of Liberty, the Terran chapter, is the "core" StarCraft II, and that Heart of the Swarm and Legacy of the Void will be equivalent to expansion packs. It has been officially confirmed that it will not be possible to play the Zerg or Protoss campaigns without already having purchased the Terran campaign.